DESCRIPTION
The invention relates to a steel link chain for chain conveyors used in underground mining or tunnel construction, with vertical and horizontal links to which are connected spaced-apart pushers and which are formed by two parallel chain link arms and chain link arches, whereby the chain link arches are shaped concavely in their mutual roll-off area in such a way that they form a surface contact area.
Such chain conveyors with interlocking chain links are used in underground mining and tunnel construction especially for transporting the mined coal and rock. Such chain conveyors are also frequently used for a wide variety of purposes underground. The chain conveyors are hereby pulled through conveyor troughs with a lateral sigma-profile in which the pushers of the chain conveyors are guided. They are subject to correspondingly high wear. In the development of such chain conveyors during the past years, only the dimensions have become increasingly larger in order to fulfill the increasing demands on performance. It is however not possible to prevent wear, but rather this wear becomes ever greater, since the contact points in the chain starwheel become smaller. Possible service lives are unsatisfactory, whereby chains with 42 mm wire diameter and more are being used.
In prior art chain conveyors, the force is applied via the chain wheels that are positioned at the ends of the conveyor trough and are equipped with drive motors. As mentioned above, the contact between chain wheel and round link chain in present standard chain conveyors only occurs in points in most cases, resulting in very high surface pressures in these contact area. Chain conveyors that have been used for longer periods therefore have distinct pitting and so-called duck rump wear in the roll-off area. This unfavorable and unsatisfactory force application represents the essential weakness of round link chains that are used almost exclusively today and limits their service life.
In order to increase the supporting cross-section, German Offenlegungsschrift 39 29 148.0 proposes that the shape of the wire forming the chain links is modified, i.e. the respective area is modified in such a way, that a larger supporting cross-section is attained.
German Auslegungsschrift 27 35 792.2-12 introduces a steel link chain with the usual round steel links and a chain starwheel in which the force is applied via the corresponding teeth.
German Patent 37 04 176.2-22 solves the problem of also combining chain wheels with stronger chain links while still utilizing existing conveyor troughs by providing the vertical links with a smaller pitch than the horizontal links. But this creates manufacturing problems, and in particular does not solve the problems of relatively high wear, especially in these stronger chain links.
Finally, German Offenlegungsschrift 39 05 754 introduces a solution in which a special design of the chain links is used to achieve a surface contact area, resulting in a significantly reduced wear. In addition, the horizontal chain links are given a special shape, so that a better force application is made possible in the chain wheel. This special shape is realized by a kind of center bridge that has an inverse tooth shape adapted to the tooth gaps. The disadvantage of this prior art steel link chain is that it is very heavy due to the center bridges, so that medium chain sizes actually are the suitable field of application. It hardly can be used with heavier chains. This prior art chain conveyor is also not optimally suited for single chain conveyors, whereby in particular the overall lengths are limited to approximately 200 to 240 m. But it was found that because of more favorable sizes of the fields, overall lengths of 300 and even 400 m are desirable. Also, additional distances are propagated where the galleries must be used a second time. In such cases, rolling curves are necessary, something for which single-chain conveyors are suited better.